


Play Along

by raindrop_rouge



Category: Shingeki no Kyojin | Attack on Titan
Genre: Airport Setting, M/M, Mikasa's Point of View, Reincarnation AU, child!Isabel, musician au, the boys are awkward, the girls are cool sisters, very supportive Mikasa
Language: English
Status: Completed
Published: 2016-06-11
Updated: 2016-06-11
Packaged: 2018-07-14 11:42:57
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,793
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/7169624
Author URL: https://archiveofourown.org/users/raindrop_rouge/pseuds/raindrop_rouge
Summary: <blockquote class="userstuff">
              <p>As they go to visit Armin, musicians Mikasa and Eren come across a pianist.</p>
<p>Eren's attention is only drawn briefly to his playing at first. But Mikasa thinks it'd be best if his attention lingered a little longer. </p>
<p>And it seems the pianist's little sister is quick to agree.</p>
            </blockquote>





	Play Along

_Final call for all passengers boarding flight E6537, to..._

Mikasa ignored the voice echoing through the waiting hall as she spotted two available seats before their gate. She moved in swiftly and dropped down into one of them, drawing her and her travel companion’s luggage up in front of the other. She’d place her handbag on the latter to make it extra clear that _yes, this seat is taken_ , but it was important to her to keep her valuables as close as possible. It always was. _Always has been_.

Keeping a tight grip on their personal belongings, Mikasa let her eyes scan the airport’s waiting room. People – _so many people_ \- were racing every which way. It was a bit dizzying, but Mikasa couldn’t say she minded. Businessmen assembled around the bright sign claiming FREE WI-FI HERE. Various groups transferring from one flight to the next shamelessly laid down on the carpeted floors near the walls, waiting for time to pass idly. Teenagers were either sat near available plugs, charging their phones and laptops, or wandering back and forth between their friends and the vending machines. Single travelers poked around the souvenir stores for last minute gifts. Couples sat in the small, open, café area. Families with younger children gathered near the floor-to-ceiling windows with a view on the take-off tracks. The toddlers bombarded their parents with questions too puzzling for them to answer coherently.

One child, however, seemed more interested in the piano that stood shyly near the wi-fi corner, than in the airplanes gliding in and out of sight. Mikasa’s gaze was caught by how vivid her hair color was, bright flames gathered by two beaded hair-ties, sticking out proudly from the top of her head. Mikasa watched as the child clambered on top of the little bench placed before the instrument.

The girl could play. Soft notes drifted into the air around her, light and cheerful.

 Unlike her expression.

As her chubby hands danced along the keys, she glared daggers at one of the many men dressed in suits, typing away at a laptop. Mikasa huffed in amusement. That child sure knew how to pout ( _not unlike Eren)._ And whoever she was glaring at now sure knew how to ignore the defiant stare ( _not unlike myself)._

“Good thing I got you a bright colored scarf, otherwise it would’ve been impossible to find you around here.”

The voice came from her right, almost startling Mikasa. Speak of the devil. She looked up to find Eren dropping a plastic bag with sandwiches and snacks onto the seat she’d saved for him. “Sorry I took so long, the line was crazy. Hope there won’t be such a long one at the restrooms, I’ll be right back,” he added, walking off again.

“I’ll wait right here!” Mikasa called after her best friend, even though he probably would’ve come back here without the assurance anyway. Her best friend whom, despite all his protests, she could not help but see and treat as a little brother. Mikasa started sorting out the food. _I give him less to complain about now though. But it’s not like he could be grateful for that_.

_She_ was grateful for it though. It was easier to give him space now, as there was a whole lot less to worry about.

Mikasa’s stomach growled loudly. She and Eren had set off early to catch a morning flight, to finally go visit Armin, their childhood friend, at his own university campus. Both had agreed to wait to get to the airport to have breakfast, decision she was regretting now.

Ah. The music had stopped. Mikasa absent-mindedly sought out the girl. It did not take long for her to find the little musician, her orange cardigan even brighter than Mikasa’s red scarf. A smile tugged at the corner of Mikasa’s lips as she noticed the rest the child’s clothing. Green skirt, pink stockings, yellow shoes, and a small purple over-the-shoulder purse- whoever had dressed her had no idea what they were doing.

Make that a ‘he’; also, scratch that thought entirely. Given how the businessman responsible for her was currently being dragged over to the piano by his sleeve, he probably had no say whatsoever in how she dressed. It was easy to see who was boss. Mikasa huffed in amusement. _Well at least he’s pretty short and doesn’t have to crouch too low to talk to her-_

Wait. Mikasa’s eyes widened.

Mikasa knew that silhouette. 

He’d been sat back to her or turned three-quarters away this entire time, but there could be no mistake.

Her entire focus now on the two individuals by the piano, her ears filtered out everything else between them.

“Big Bro, play,” the little girl was demanding.

“That’s enough, Izzy, you’re gonna be sat down for hours on the damn plane, go check out the take-off tracks, or the shops, or some shit. As long as I can see you,” the dark hair man replied, his tone not nearly as commandeering as his protégé’s had been.

“Don’t swear,” ‘Izzy’ spoke tersely. “Now play, Big Bro,” she ordered again.

“Listen, Izzy, there’s still a few emails I need to-“

“ _Levi_ ,” the child growled. Which would’ve been downright hilarious under different circumstances, but the effect was immediate on the two adults listening to her. Mikasa inhaled sharply, snacks in her lap rolling onto the seat next to her unnoticed, while Levi’s jaw dropped open. Clearly, the absence of the affectionate nickname was going to get the child what she wanted. There was a moment of silence between them all, before Izzy’s face morphed from a mask of pure, unbridled, child rage, to an expression of deep disappointment.

“B-but, you p-promised me that if I went to b-bed early last night, you’d p-play with me,” the child mumbled pitifully, bottom lip quivering, big green eyes looking up at her brother. “And I d-did, right? We haven’t p-played together in a long time, I m-miss it,” she continued, staring down at her feet now.

Mikasa stared on, half amused, half in awe, as Levi frantically tried to calm his little sister down.

In no time flat they were both sat at the piano, playing another happy little tune.

Mikasa smiled. She knew this one. Her hands started dancing on their own in her lap, as her eyes finally drifted away from the siblings. They came to rest instead on Eren’s violin case, where it lay by her feet.

She sighed. Maybe it wasn’t that much of a surprise that Levi would be skilled at something as delicate as piano playing. Hmm. She supposed he would be, all things considered. She nodded along to the song for a little longer, lost deep in thought.

“Everything ok, Mikasa?” Eren had finally returned.

“Ah…” Mikasa’s fingers froze. The next second, her hands were racing to gather up the food. Before Eren could inquire any further, Mikasa shoved a sandwich to his chest. “Here, you eat this for now.”

Eren grinned. “What do you mean, ‘for now’, am I being rationed or something?”

A loud growl from his stomach had him grimacing, and saved Mikasa the trouble of giving a coherent answer.

“I sure hope not,” he sighed, dropping down into his seat, as they both finally started eating their breakfast. Mikasa’s eyes kept jumping from her best friend to the short pianist, in one of her rare moments of indecisiveness.

“By the way, do you know if we even get food during our flight? Or was that an extra we had to sign up for? Please tell me it wasn’t,” Eren asked around a mouthful of food, bringing her back to the present moment.

“I can’t remember, let me check,” Mikasa replied distractedly, setting down her food on a napkin and fumbling through her purse. She pulled out the two boarding passes she’d printed out a few days before.

“Hmm… well it just says that snacks can be ordered, so I’m not sure. Meals probably depend on the time and how long the flight lasts. I’m not sure ours is long enough for us to qualify.”

“Ugh… oh well,” Eren grumbled, too focused on his sandwich to complain more.

Mikasa was relieved that was enough of an answer. She needed to reorganize her thoughts.

She glanced down at their tickets once again. Seats 14C and 14D. They didn’t usually get to be sat next to each other on flights, ever since they’ve been old enough to take care of their own tickets and travel unaccompanied by adults. Mikasa would remember to register as soon as online check-in would open, and deal with it as soon as possible. Eren, on the other hand, was an expert at forgetting until the very last minute. To avoid worrying about that at way-too-early o’clock in the morning, Mikasa had offered to check them both in at the same time. Eren had thanked her, before promptly forgetting all about it. He never even asked her for his papers until they had to pass security, and then automatically handed them back to her, without sparing them a glance.

Ah well. She didn’t mind. He’d manage on his own if he really had to (or at least, she and Armin kept telling themselves that). She began to fold up the documents in her hands again.

“Hey Mikasa, it’s that song you used to play a lot when we were younger,” Eren suddenly exclaimed, reaching for their drinks now he’d finished his food. “Wait, where’s it coming from… oh neat a piano!”

Mikasa’s hands instantly stilled around the papers.

Her eyes shot up, the need to watch Eren’s face in that moment overwhelming. The need to _know_.  

Eyes gleaming in excitement, an easy smile on his lips, just a hint of fatigue reflecting how little sleep he’d gotten the night before.

In other words, nothing.

His wide eyes were trained straight on Levi’s back, yet his all reactions related to no more than the finding of a piano and the music drawn from it. The complete absence of a particular response made Mikasa’s heart sink. It hurt, far more than she’d ever expected. It was another sharp reminder that she still sometimes forgot. Eren was not all she projected upon him. All she thought he was. _All I once_ knew _he was_.

In that moment, a unique, yet very familiar gaze on her best friend’s face was loud in its absence. Mikasa hadn’t even realized until then how she’d come to assume certain emotions were an integral part of Eren’s essence. It was weird. Out of the natural order of things. She was discovering all over again how much things had changed.

But then, Levi slid effortlessly into another song, Izzy most likely having made a request from where she stood at his side, back on the floor. A far softer melody floated past their ears, one Mikasa had never heard before. But Eren’s face brightened up even more.

Ah well. _Something_ about this pianist was bound to have an impact at some point.

Just as Mikasa was regaining hope, Eren shifted, turning back around to face her. “Oh, by the way, Mikasa, I owe you snacks now. I grabbed money you’d left on the kitchen counter before leaving, just in case you’d meant to take it, and I just realized that’s what I used to pay for all this.”

“No worries,” Mikasa murmured quickly, and obstinately kept her eyes on the piano. Hopefully Eren would follow her lead and shift his focus back onto the musician too. _He has to_ , Mikasa thought anxiously.

It dawned upon her that she was determined to make sure Eren properly acknowledged the pianist. Why exactly that was, she couldn’t say. Maybe it was simply that she’d feel guilty if she didn’t do all in her power for Eren’s good. But how could she be really sure that this was for the best? She had _just_ been contemplating how things had changed.

It was already too late to reconsider. Of course her dismissive response would work. Eren was only too happy to avoid the expected lecture on grabbing money off counters and not mentioning it.

Eren swayed gently to the music for a few moments. Mikasa waited.

Eren began throwing quick glances to his violin case. Mikasa chewed on her lip.

Eren’s fingers began to twitch. That was enough.

“Listen,” she blurted suddenly. Which she instantly regretted, and forced herself to take a long breath before continuing. She could not afford to come across as forceful. Nothing was ever accomplished with Eren that way. At the same time though, subtlety was not going to cut it. “If you know the song, you should join in. You clearly want to.”

Her friend was not going to fight something he felt like doing, of that much she was certain. But because everything had to be complicated in this world, apparently, he sputtered out a protest.

“I can’t just start improvising with anyone, you know,” he muttered, glancing down. Of course he was avoiding her stare as he said that, knowing he’d find raised eyebrows.

Which didn’t mean he could avoid hearing her obvious reply.

“Oh really. Funny, I’m pretty sure that’s exactly how we met.”

She’d been really happy, though, the day she’d been playing all alone, in what she thought was an empty room, in an empty hallway, of their (almost) empty music school, and the bright eyed boy had barreled in. Even when he’d barely had a proper grip on his instrument, it was more fun to play however they wanted together, than to repeat assigned measures again and again.

Admittedly, it all only started sounding decent after they had repeated those measures, and countless whole music sheets, again and again, for entire years.

But here they were now, attending a prestigious music school together. And no matter how much classical music they were put through there, their friends knew that what was truly _them_ came through when they improvised together.

It started off as the kind of thing aspiring band members would do. Get together in a garage and see if they could come up with anything half bearable to listen to. Except they’d get together in Mikasa’s fancy living room, where her piano stood, and Eren would play whatever he wanted, with complete disregard for anyone else’s ear sensibilities.

How _good_ their instruments eventually started sounding together definitely came as a surprise to everyone. Armin even needed convincing his musical expectations hadn’t simply fallen incredibly low over time. But Mikasa and Eren learned to intuitively combine known pieces of music beautifully. They learned to know each other’s style to anticipate shifts or complete changes in tunes, enabling them to entwine their music harmoniously, and create a naturally flowing melody.

They didn’t ever plan performances. They just happened wherever there was a piano and Eren happened to have his violin with him. Which turned out to be very often.

Right now, Eren technically had all he needed: a pianist, and his own instrument.

“Come on, it can’t possibly be that different to improvising with me? What did you think improvising even meant?” A huff. “He even sort of looks like me,” Mikasa added, tilting her head to the side as if to get a better view.

“You’re nowhere near that short.” A pause.

“Hmm, what’s that? How do you know he’s short?”

Eren opened his mouth, obviously about to say “Because you can tell”, before promptly shutting it, because you obviously couldn’t, from where they were, observing a man sat down. His brows furrowed slightly as he fumbled for an answer he didn’t have.

Mikasa’s lips twitched up as she spoke her next words. “Well, nothing wrong with being a bit short, right?” Oh, if she had known she’d ever be the one saying that to Eren.

 “No! Of course not!”, too loudly. Ah, there it was. The automatism she’d hoped for. Confusion was starting to paint itself all over Eren’s face in a way that might be permanent though.

“Alright then,” Mikasa said, stretching her leg out to toe at the violin case, and using it to push Eren away, “Have fun!” she waved, with a smile only he’d be able to detect. If even he.

She watched her friend grab his violin and stomp over to the piano, muttering “fine, _fine_ ” under his breath. Mikasa was not fooled.

She sorely wanted to call Armin right then, but she could not take her eyes away from the two men. Back stiff, hands still curled tight around their boarding passes in her lap, she watched Eren wordlessly pull out his violin, back to the wall, near the other musician.

As Eren’s eyes found the pianist’s face, he froze for a moment. Mikasa clasped her hands together with a gasp, ignoring the sound of crunching paper. She held her breath. Was it possible, that after all this time, maybe-

But no, Eren had only been looking for a good point in the music to come in.

After a long inhale, he proceeded to do so. A slow, sad melody rose into the air, subtly complementing the gentle sounds of the piano. This was unusual for Eren. If Mikasa was working on a rather sober song, Eren would find a way to infuse displaced energy back into it. She supposed Eren was more inclined to respect whatever tone Levi set a lot more than whatever she might do. No wait, here he was probably just showing the respect due to a stranger he was technically interrupting.

Oh, no. Why did neither of them realize this immediately? O _f course_ this would be deemed as interrupting. Possibly even rude. Definitely rude. This is why she should have taken the time to call Armin before doing anything, he was better at dealing with _all of this_ than she was, what seriously were the odds of this going well at all?

“Hey there.” A small voice interrupted Mikasa’s increasingly anxious internal monologue. “I’m Isabel, nice to meet you.”

Mikasa looked down to find big green eyes peering up at her from beneath bright hair. She acknowledged the little girl’s words with a nod. She didn’t mind children, but she didn’t know how to interact with one either. Isabel wasn’t moving, her eyes trained on Mikasa. Well then. If she had something to say, she’d say it eventually. Mikasa turned back to the two musicians.

No one else in the waiting hall seemed to be paying them any particular attention. Some had turned to see where the music was coming from, before going right back to minding their own business. Those who looked sometimes smiled briefly, the general consensus apparently being that the music was enjoyable. Or at least adequate for airport waiting halls.

Eren looked very pleased with his own playing. His eyes were shut, as they only rarely were, and he had a peaceful air about him. Mikasa fought down a fond smile. Her gaze swung over to the short pianist.

His back and shoulders had visibly stiffened, and, for someone with Mikasa’s piano experience, his playing had audibly become more tense. By the way his head barely, but sharply, snapped to the side, Mikasa knew he was throwing Eren worried glances. This time, Mikasa fought down a grimace. Guess he didn’t change all that much either.  She began chewing on the inside of her cheek as it occurred to her that, maybe _he_ -

“He’s not gonna like that,” Isabel chirped up again. “Big Bro will hardly let _me_ play along at home.”

Mikasa had nothing to say to that. Her shoulders slumped however, as she realized, from the little body language she could read from where she was, that Levi did look annoyed. Eren must have felt it, but was choosing to ignore it. Ah well.

He didn’t owe him anything this time around.

“You look like Big Bro.” There was no question in that statement. “Are you family?” Whether that was truly a question or not was far less clear than it should have been.

Mikasa finally moved to face the girl. There was only one honest answer to that. But to Mikasa, it would not have been the truth. She was not willing to lie; and a silence would have been telling anyway.

Isabel was waiting patiently for her answer. Mikasa looked down, and only started noticing the eager gleam in those bright eyes. A gleam that would cause most children ramble on and on until they got what they wanted.  

Finally, Mikasa understood.

She took in a short breath. Worst case scenario, she was wrong, but normal children liked stories anyway.

“Maybe. In another life.”

She watched as Isabel’s eyes widened infinitesimally.  She opened her mouth to reply, but both girls froze and looked over to the piano, as its music stopped abruptly.

Mikasa’s heart sank as she watched Levi stomp away.

Unexpectedly, though, Eren did not carry on like he sometimes would when Mikasa dropped off. Instead, the girls observed as he ran after Levi. He looked like he would’ve grabbed the pianist’s arm to drag him back, but his hands were still holding his bow and violin. In his haste, he’d forgotten his case on the floor.

Mikasa flinched as she bit down a bit too hard on her cheek. She did not stop staring.

“Could he also have been… family, in another life?” Isabel murmured, loud enough for only her to hear.

Slowly, Mikasa nodded.

A grin framed by chubby cheeks spread over Isabel’s face. “Big Bro was always Big Bro to me.” This might have sounded puzzling, but Mikasa had heard eventually. From Eren, briefly. And she remembered. She knew. She watched the unnaturally-independent-for-her-age child wave at Levi, who had nervously started searching for her.

“Pfft,” Isabel muttered, tone contrasting with the smile still painted on her face, as she signaled her position to her brother, “where else would I possibly go? This is our gate, what a worrywart.”

Oh. They’d be boarding the same plane then.

Levi was about to head their way, probably ready to scold Isabel for wandering off, but Eren stopped him again. Mikasa cringed. She was glad Eren was trying to talk to the man, but she’d prefer he didn’t get himself killed while trying.

“So…,” the child started, hoisting herself into Eren’s abandoned seat, “your name is…?”

Mikasa looked at the child for a long moment before holding her hand out.

“Mikasa. And it’s nice to meet you too.”

All things considered, it definitely should’ve been a weird sight, a little girl coming up to her, unsupervised, and striking up conversation. Then again, maybe everyone was caught up in their own travel stress, or too busy daydreaming about their beginning vacations. Or, Mikasa thought bitterly, it wasn’t all that unusual at all for parents to lose sight of their children, and no one saw anything wrong with that. In any case, she and Isabel were left to chat freely.

Isabel talked about Levi. She told Mikasa about how her parents had adopted him when they thought they couldn’t have children of their own, which explained the big age gap between them. He had, in fact, encouraged his parents to keep her, and had practically raised her himself. So of course she’d started playing the piano early, sticking around during his own lessons.

It was odd, listening to Isabel speak. She brought up topics no girl her age should be able to discuss with the understanding she displayed, but kept the mannerisms of a child, struggling to pronounce longer words properly. She was sweet, but her speech was difficult to focus on, and Mikasa’s thoughts drifted elsewhere as Isabel started explaining how “Big Bro” had this weird way of placing his hands over the keys, but at least it didn’t affect his playing.

Mikasa caught herself throwing increasingly frequent glances over to the two men. It probably was neither polite nor discreet vis-à-vis Isabel, but she found it impossible to prevent herself from keeping an eye on them.

Eren had caught up with Levi yet again. This time, however, the brunet was managing to make him listen to whatever he had to say. Levi stood perfectly still, in stark contrast to Eren, who was visibly agitated. He was gesticulating, with little regard for the ( _expensive_ ) instrument still in hand. At one point he reached up, no doubt his nervous habit of rubbing his hand against his neck, and almost took out another passenger with his bow. He hardly noticed.

His furrowed brows gradually gave way to a hopeful expression, his eyes lighting up as a broad smile graced his boyish features. Oh, what was he getting himself into now. Was he blushing? It was hard to tell from where Mikasa sat. If he just turned a bit the sunlight would reach his face and she would be able to see for sure… Nevermind, from the way he was nervously laughing, he might as well be.

Mikasa’s next peek was directed at Levi. The peek turned into a glare. _Why_ was he so expressionless, couldn’t he _try_ to be nice? He was going to make Eren feel terrible for interrupting him. He was going to make Eren regret going up there to play too, when really Eren could have been doing them both a huge favor.

Would it hurt him to _stop_ frowning?

She was beginning to feel her nails cut into her palms, fingers wrapped tight around slips of paper, and Isabel’s voice finally reached her again.

“Woah, hey, calm down! I know it may not look great, but, uhm, Big Bro is usually a _lot_ nastier with strangers. I mean. A whooole lot,” she said, stretching her arms out in an attempt to quantify “a lot”. “I’m surprised he’s even bothering to stay and chat at all. Like, your friend _interru’ted_ his playing. When I do that, I have to beg for forgivess,” she grinned, ignoring her mispronunciation of “interrupted” and “forgiveness”. “And I’m his cute lil sister, and he adores me,” she added with an exaggerated wink.

Mikasa relaxed, and a small laugh almost escaped her lips. Levi as a doting older brother. A protective older brother. She stared at the man some more and decided, maybe that wasn’t terribly far from what she’d known of the man after all. Again, Isabel’s voice rose, bringing her back to the present.

“I wonder what those two could have been, in another life,” she said, tilting her head to the side.

At those words, Mikasa could feel the nostalgic smile spread over her face, no matter how hard she tried to bite it down.

“Family too… eventually.”

She tore her eyes away from the two men, Eren gleefully dragging Levi over to the waiting hall’s café, as she felt two little hands tug her fingers apart.

“Your knuckles keep cracking. Your fingers will hurt when you grow old.” Mikasa almost replied that her knuckles had known much worse.

“That’s a myth, you know,” she answered instead.

Isabel’s expression grew dark. “I knew it, he’s been lying to me about that!”

Suddenly, one corner of her mouth twitched up. With a sly look, she began digging into her purple purse.

“Ya know what… I feel like there’s a lot more you might tell me that Big Bro wouldn’t… or couldn’t.”

Well, given that “Big Bro” seemed completely lost in her best friend’s eyes right now, there probably wasn’t much he’d be telling anyone anytime soon.

The little hands were on hers again, but this time they were loosening her grip with purpose. Mikasa opened her mouth to protest as Eren’s crumpled boarding pass slipped between her fingers.

“Internal flight,” Isabel cut in first. “I’ve been to this airport a million times, they won’t recheck ident’y at this point, trust me. And half these million times I’ve been seated alone. Big Bro won’t worry.”

Mikasa raised an eyebrow. If Levi was anything like what he used to be, or anything like herself, that was definitely a lie. But as far as she could tell, Isabel’s brain worked like Eren’s. There was no use trying to explain, or to change her mind.

Instead, she stared, resigned, at her hands, where the smaller ones were shoving a different, but equally crumpled boarding pass into her grasp.

“Give this to your friend, ok? I’ll see you on the plane,” Isabel sung as she darted off again.

Mikasa hid a grin behind her scarf as a lively tune filled the air.

Ah. Of course Levi was back at the piano. Was she only imagining that the tips of his ears were red?

Eren was going to owe her a whole lot more than snack money.

**Author's Note:**

> This fandom needs more Izzy-Mikasa interactions!!! And I just really wanted that. Maybe I'll write some with them being the same age, in the future (emphasis on maybe).   
> Also, I can't imagine Mikasa being anything less that extra-super supportive of anything that she knows makes Eren happy. That's my stance on the issue.
> 
> Thank you so much for reading! <3
> 
> Follow me @raindrop-rouge on tumblr~


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